Commercial 3D Printer Research Articles

Physical Characterization of Injectable Bone Substitute Associated-3D Printed Bone Scaffold for Spinal Tuberculosis

There are two important factors to overcome spinal tuberculosis, i.e. killing and preventing the Mycobacterium tuberculosis to spread, also replacing and reconstructing the damaged bone. This study focused on an innovation to overcome the spinal tuberculosis problem by combining the IBS and 3D printed bone scaffold. This innovation could provide a local drug delivery system along with tissue regeneration and bone reconstruction. In this study, 3D printed bone scaffold which have been injected with IBS were tested its physical characterizations. The bone scaffold was fabricated from Polylactide acid (PLA) filament using FDM method through an ordinary commercial 3D printer. The IBS was synthesized from nanohydroxyapatite, gelatin, streptomycin, and HPMC. The physical characterization performed in this study were porosity test functional group test, and degradation test. From those characterizations, it could be concluded that the IBS associated-3D printed bone scaffold is a potential alternative to overcome spinal tuberculosis.

Additive manufacturing and characterization of a load cell with embedded strain gauges

In this paper we present the exploitation of Fused Filament Fabrication (FFF) to manufacture a load cell using double extrusion of conductive and non-conductive commercial materials in a single-step printing cycle. A load cell with four embedded strain gauges, manufactured with tailored process parameters and strategies, was used to deposit the conductive filament to obtain near equal electrical resistance values among the four strain gauges, aiming to connect them in a full Wheatstone bridge configuration. Subsequently, several tests were performed, firstly to understand the behavior of each strain gauge and then to characterize the load cell. The tests showed that the strain gauges are sensible to compressive and tensile deformation and that the load cell's voltage, obtained by connecting the four strain gauges in a full Wheatstone bridge, decreases as the force applied increases. This work demonstrates the potential of FFF technology in the sensor manufacturing field and that it is possible to integrate sensitive elements into non-sensitive elements without an additional assembly process by using low-cost commercial filaments and 3D printers.

Effects of thermal process parameters on mechanical interlayer strength for additively manufactured Ultem 9085

The effects of the envelope temperature on the microstructure and mechanical strength of Ultem 9085 fused deposition modeling (FDM) components were studied. A customized build chamber was developed for a commercial 3D printer in order to control the envelope temperature during printing. Test specimens were printed in the vertical direction because their mechanical strength exhibited the greatest dependence on inter-layer adhesion and neck development. A delay was introduced between two layers in each specimen in order to create a weak region where the neck was not expected to fully develop. However, none of the specimens failed in this region. Mechanical testing revealed that neck growth was highly dependent on the envelope temperature, and the strength was shown to vary significantly (>20%) based on the envelope temperature. The variability of the mechanical strength also decreased as the envelope temperature increased. Thermal imaging revealed that the cooling rate of the specimens was consistent regardless of the envelope temperature. Fracture analysis confirmed that higher envelope temperatures improved the amount of neck growth and inter-layer adhesion in the specimens. This study showed that increasing the envelope temperature created parts with higher strengths and improved consistencies.

Miniaturized additively manufactured co-laminar microfluidic glucose biofuel cell with optimized grade pencil bioelectrodes

Miniaturization of enzymatic biofuel cell has become a crucial factor especially towards device fabrication and integrated bioelectrode system. When successful in a cost-effective manner, it can be used as a source of qualitative electric power for portable and implantable devices. The present work demonstrates the design and fabrication of cost-effective, portable, miniaturized microfluidic enzymatic biofuel cell (M-EBFC) using rapid prototyping 3D printing (3DP) technique. The low cost, radially available, non-toxic Pencil Graphite Electrodes (PGE's) were used as the electrode material. Various grades of PGE's were rigorously studied, by screening separately and cohesively for both anodic and cathodic sides, and the optimized ones (B and 5H for anodic and cathodic sides respectively) have been utilized. These PGE's successively encapsulated into Y-shaped microchannel, fabricated using a commercial 3D Printer. This platform, integrating 3D printing technology and PGE's, delivers simplistic, cost-effective and quick fabrication method, which eradicates the necessity of any further amendment and post-processing. Furthermore, the enhancement of the surface area and electrochemical sensing, PGE's were coated with carboxylated multiwalled carbon nanotube followed by the covalent immobilization enzymes. The electrochemical and polarization performance was compared between both HB and the optimized PGEs. The optimized PGE based 3D printed microfluidic membraneless enzymatic biofuel cell (3DP-MM-EBFC) showed open circuit potential (OCP) of 0.433 V and with a maximum power density of 18 μW cm−2 at a current density of 60 μA cm−2. This rapidly prototyped 3D printed fabrication technology demonstrates the viability of simple and advanced microfabrication techniques to build well-organized plug-and-play devices to power several portable low-power microelectronic devices and sensors.

Demonstration of soft X-ray 3D scanning and modeling with a glass gas electron multiplier

A new detector, based on an optical-readout glass gas electron multiplier was developed for a soft X-ray CT scanner. Soft X-ray imaging (<20 keV) provides high-contrast images of low-Z elements, such as soft tissues. We model a three-dimensional (3D) copy of a low-Z object with a high-resolution gaseous detector and a 3D printer. The detector was used to acquire high-resolution images to reconstruct a 3D computed tomography (CT) image. As an example, a fine 3D X-ray CT image of a hornet was reconstructed with high contrast. The 3D CT data were converted into 3D computer-automated design data, and a copy of the scanned object was printed with a commercial 3D printer. Overall, this work demonstrates a new use of gaseous detectors, rapid and precise soft X-ray 3D scanning, and modeling of soft tissues.

Design of 3D filament extruder for Fused Deposition Modeling (FDM) additive manufacturing

Filament extruder produces plastic filaments with specified diameter by using corresponding dies. Input materials (thermoplastics) are used in the form of granules and pellets and waste plastic materials can be used. Rod heaters are used to melt the input materials and Screw is used to feed the input raw materials longitudinally along the barrel. Screw is consisted of three zones namely feed, melt, and transition zone. Input raw material is melted by using rod heater. Two temperature zone with six rod heaters are used to acquire maximum efficiency. Analog temperature controller is used to control the temperature of the two heaters zone. This article describes a filament extruder, which is a plastic extruder capable of making commercial quality 3D printing filament. Specifically, this paper describes the design, fabrication and operation of a filament extruder. A 2.5 mm die was used to extrude the filament at the diameter of 1.75mm. Diameter of the filament can be further reduced by using DC-motor to draw the filament coming out of the die. Production can be further increased by increasing the barrel diameter above 45mm and screw diameter above 16 mm. Mechanical and thermal properties were improved by adding different fillers to the input raw material

Next-Generation 3D Printed Microfluidic Membraneless Enzymatic Biofuel Cell: Cost-Effective and Rapid Approach

3D printing offers a novel, time-efficient, and multi-material fabrication platform for numerous applications owing to its potential to rapidly manufacture low-cost and 3D printed (3DP) structures. In this paper, polylactic acid (PLA) and conductive composite graphene/PLA filaments were used to fabricate 3DP microchannels and electrodes intended for enzymatic biofuel cells (EBFCs) using a commercial bench-top 3D printer. This 3D printing technology delivers a simplistic, cost-effective, and quick fabrication process, which eliminates the requirement of any further amendment and post-processing. With this technology, we demonstrate structurally simple, miniature 3DP microfluidic membraneless EBFCs (3DP-MM-EBFCs), served with glucose and oxygen with the utilization of redox mediators generating continuous power. The cell performance was evaluated at different flow rates, obtaining open circuit potential (OCP) 0.425 V and maximum peak power density (PD) $4.15~\mu \text{W}$ /cm2 at a current density (CD) of $13.36~\mu \text{A}$ /cm2. The advancement in 3DP electrode surface characteristic and the dimethylformamide (DMF) treatment is carried onto the electrode surface followed by the immobilization of the enzymes individually. The 3DP fabrication technology demonstrated the feasibility of simple and advanced microfabrication techniques to build a well-organized plug-and-play and rapidly analyzed device to power several portable low-power devices.

Zinc oxide/clove essential oil incorporated type B gelatin nanocomposite formulations: A proof-of-concept study for 3D printing applications

Bioactive bovine skin gelatin (BSG)/zinc oxide (ZnO)/clove essential oil (CEO) nanocomposites films were fabricated by a solution-cast. The suitable combinations of ZnO (2 wt%) and CEO (25 wt%) improve the desirable film properties, namely, elongation at break (EAB), optical, structural, thermal, barrier and microbiological properties. XRD confirmed the presence of ZnO in the gelatin-composites and the highest thermal stability of the composites was evident by the TGA thermograms. Currently, additive manufacturing has received serious attention in the development of complex structures in the tissue engineering and allied areas, with tailored properties. In this work, the optimized formulation was further explored for its potential applications in 3D (bio) printing. The BSG/ZnO/CEO blend was converted into a semi-solid viscous mass by means of a twin-screw extrusion process. The extruded materials were utilized further to develop 3D printable bioinks in the presence of sodium alginate polymer. Round shaped thin alginate-based films (D × H = 10 mm × 1 mm) were printed via a commercial 3D printer (cross-linked with 100 mM CaCl2 solution). This technique could bring advantages and superiority over the conventional processes, with the competence of generating reproducible, tailored, and functional structures, which could effectively endorse regeneration of different tissues and can be used across the disciplines including food packaging and food printing.

Mechanical properties and energy absorption of 3D printed square hierarchical honeycombs under in-plane axial compression

Hierarchical structural design was considered as a promising approach to improve the performance of regular cellular materials. In this study, square hierarchical honeycombs (SHHs) were fabricated by employing a commercial 3D printer, and their in-plane mechanical properties and energy absorption were investigated. The SHHs were constructed by replacing each solid cell wall of a regular square honeycomb (RSH) with different numbers of smaller square substructures. In-plane quasi-static compressive tests were conducted on SHHs, and the effect of substructure number on the deformation mode, mechanical properties and energy absorption performance were studied. The results revealed that the cells of SHHs and RSH collapsed layer-by-layer along the loading direction, while more localized bands and damage were found for SHHs. Enhanced compressive strength, specific energy absorption and crush force efficiency were found for SHHs when compared with RSH of equal mass. Moreover, the reason for the enhancement and the effect of substructure number on the enhancement were also explored. In addition, analytical expressions for the Young's modulus and compressive strength of SHHs were developed, and the results from experiments and simulations were employed to verify the analytical results. This study elucidates the effect of structural hierarchy on the mechanical properties and energy absorption performance of regular cellular materials.

The mussel-inspired assisted apatite mineralized on PolyJet material for artificial bone scaffold.

With the development of three-dimensional (3D) printing, many commercial 3D printing materials have been applied in the fields of biomedicine and medical. MED610 is a clear, biocompatible PolyJet material that is medically certified for bodily contact. In this study, the polydopamine (PDA)/hydroxyapatite (HA) coating was added to the printed MED610 objects to evaluate its physical properties, cell proliferation, cell morphology, and alkaline phosphatase expression level. The results show that the PDA/HA coating helps printed objects to enhance the hardness, biocompatibility, and osteogenic differentiation potential. We expect that PDA/HA coatings contribute to the applicability of MED610 in biomedical and medical applications.

Vat photopolymerization 3D printing of ceramics: Effects of fine powder

The objective of this work is to test a novel approach to increase the bulk density of ceramic parts made by vat photopolymerization. It is hypothesized that the bulk density of the resultant ceramic parts increases by introducing a small amount of fine powder to the suspension feedstock. A commercial 3D printer was used to produce samples from different suspensions. The printed samples then underwent debinding and sintering processes, after which density and porosity measurements and microstructural characterization were carried out. It could be summarily concluded that the substitution of a small volume of a coarser (0.8 µm) powder with a finer powder (0.3 µm or 0.5 µm) in the suspension markedly increased the bulk density and decreased apparent porosity of the printed and sintered parts without worsening the printability of the suspension. Scanning electron microscopy showed the fine powder improved the necking during sintering, contributing to the increased density and decreased porosity.

Robust Surface-Engineered Tape-Cast and Extrusion Methods to Fabricate Electrically-Conductive Poly(vinylidene fluoride)/Carbon Nanotube Filaments for Corrosion-Resistant 3D Printing Applications

We developed a poly(vinylidene fluoride)/carbon nanotube (PVDF-MWCNT) filament as a feed for printing of electrically-conductive and corrosion-resistant functional material by fused filament fabrication (FFF). Using an environment-friendly procedure to fabricate PVDF-MWCNT filament, we achieved the best reported electrical conductivity of printable PVDF-MWCNT filament of 28.5 S cm−1 (90 wt% PVDF and 10 wt% CNT). The PVDF-MWCNT filaments are chemically stable in acid, base, and salt solution, with no significant changes in electrical conductivity and mass of the filaments. Our processing method is robust and allow a uniform mixture of PVDF and CNT with a wide range of CNT percentage up to 99.9%. We demonstrated the printing of PVDF-MWCNT filaments to create 3D shapes; printed using a low-cost commercial consumer-grade FFF 3D printer. We found many adjustments of printer parameters are needed to print filament with CNT content >10 wt%, but easier printing for CNT content ≤10 wt%. Since this was due to printer limitation, we believed that PVDF-MWCNT with higher CNT percentage (to a certain limit) and larger electrical conductivity could be printed with a custom-built printer (for example stronger motor). PVDF-MWCNT filament shows higher electrical conductivity (28.5 S cm−1) than compressed composite (8.8 S cm−1) of the same 10 wt% of CNT, due to more alignment of CNT in the longitudinal direction of the extruded filament. Printable PVDF-MWCNT-Fe2O3 (with a functional additive of Fe2O3) showed higher electrical conductivity in the longitudinal direction at the filament core (42 S cm−1) compared to that in the longitudinal direction at the filament shell (0.43 S cm−1) for sample with composition of 60 wt% PVDF, 20 wt% CNT, and 20 wt% Fe2O3, due to extrusion skin effect with segregation of electrically insulating Fe2O3 at the shell surface of PVDF-MWCNT-Fe2O3.

Development of a Low Cost 3D Printer Indicated to Prototyping Objects

A indústria 4.0 vem impactando a cadeia produtiva refletindo no desenvolvimento tecnológico sustentável, sendo que o uso da impressão em 3D se encontra entre as tendências que devem criar novas oportunidades de negócios, como confecção de peças personalizadas e de difícil aquisição, entre outras. Em países como Brasil a impressora 3D comercial ainda possui elevado custo. Assim, este estudo teve por objetivo desenvolver uma impressora 3D de baixo custo, aplicando o método RepRap de auto replicação, testar, calibrar e imprimir peça para comparar com uma impressora comercial similar certificada. Realizou-se a montagem de uma impressora similar ao modelo Prusa i3 com o firmware Marlin utilizado para controle de seus componentes e software Repetier para sua configuração e controle. Como resultado foi desenvolvida a impressora 3D configurada e calibrada realizando-se a comparação de qualidade imprimindo uma peça na impressora 3D de baixo custo e em impressora comercial certificada. Também foram fabricadas peças como tela protetora e suporte para filamento, visando a melhoria do projeto. Com esta pesquisa foi possível concluir que é possível desenvolver uma impressora 3D RepRap de baixo custo se comparada à impressora comercial certificada com características idênticas quanto a precisão na qualidade final da impressão.

Additive manufacturing ferromagnetic polymers using stereolithography – Materials and process development

Magnetic field responsive polymer composites find applications in many electrical and electronic devices. In this study, composites with magnetic fillers were manufactured using a stereolithography based AM process. Magnetic suspensions developed with an objective of controlling particle settling were characterized for rheological properties. A stereolithography based commercial 3D printer was utilized to fabricate components using the developed magnetic suspensions. Resulting magnetic composite structures were characterized using scanning electron microscopy, a coordinate measuring machine and Fourier transform infrared spectroscopy. Through this research an enhanced understanding of filler modified polymers development, material behaviour and the process for manufacturing magnetic field responsive composites using stereolithography is obtained.

The Dynamic Response of Dense 3 Dimensionally Printed Polylactic Acid

Polylactic acid (PLA) is commonly used as a feedstock material for commercial 3D printing. As components manufactured from such material become more commonplace, it is inevitable that some of the resultant systems will be exposed to high strain-rate/impact events during their design-life (for example, components being dropped or even involved in a high-speed crash). To this end, understanding the shock properties of polylactic acid, in its role as a major raw material for 3D printed components, is of particular importance. In this work, printed samples of PLA were deformed by one-dimensional shock waves generated via the plate impact technique, allowing determination of both the Hugoniot Equation of State (EOS) and shear strength of the material. Both linear and non-linear EOS forms were considered in the US-Up plane, with the best-fit found to take the general form U_{S} = 1.28 + 3.06 - 1.09U_{p}^{2} in the U_{s} {-}U_{p} plane, consistent with other polymers. Use of lateral Manganin gauges embedded in the material flow allowed consideration of lateral stress evolution at impact pressures ranging from 0.3 to 4.0 GPa. Shear strength was observed to increase with impact stress, however, with minimal strengthening behind the shock front. Deviation of the measured stress from the predicted elastic measurement (corresponding to the PLA’s Hugoniot Elastic Limit) was observed at longitudinal stress of 0.90 ± 0.05 GPa, within range of polymeric materials of similar characteristics—the first time this important parameter has been measured for PLA. As a result, this material characterisation will allow numerical modellers to accurately predict the structural response of PLA-based components/structures against high strain rates such as impacts or drops.

Three-dimensional Patterning of Engineered Biofilms with a Do-it-yourself Bioprinter.

Biofilms are aggregates of bacteria embedded in a self-produced spatially-patterned extracellular matrix. Bacteria within a biofilm develop enhanced antibiotic resistance, which poses potential health dangers, but can also be beneficial for environmental applications such as purification of drinking water. The further development of anti-bacterial therapeutics and biofilm-inspired applications will require the development of reproducible, engineerable methods for biofilm creation. Recently, a novel method of biofilm preparation using a modified three-dimensional (3D) printer with a bacterial ink has been developed. This article describes the steps necessary to build this efficient, low-cost 3D bioprinter that offers multiple applications in bacterially-induced materials processing. The protocol begins with an adapted commercial 3D printer in which the extruder has been replaced with a bio-ink dispenser connected to a syringe pump system enabling a controllable, continuous flow of bio-ink. To develop a bio-ink suitable for biofilm printing, engineered Escherichia coli bacteria were suspended in a solution of alginate, so that they solidify in contact with a surface containing calcium. The inclusion of an inducer chemical within the printing substrate drives expression of biofilm proteins within the printed bio-ink. This method enables 3D printing of various spatial patterns composed of discrete layers of printed biofilms. Such spatially-controlled biofilms can serve as model systems and can find applications in multiple fields that have a wide-ranging impact on society, including antibiotic resistance prevention or drinking water purification, among others.

Acoustic Focusing Enhancement In Fresnel Zone Plate Lenses

The development of flat acoustic lenses for different applications such as biomedical engineering is a topic of great interest. Flat lenses like Fresnel Zone Plates (FZPs) are capable of focusing energy beams without the need of concave or convex geometries, which are more difficult to manufacture. One of the possible applications of these type of lenses is tumor ablation through High Intensity Focused Ultrasound (HIFU) therapies with real time Magnetic Resonance Imaging (MRI) monitoring. In order to be MRI compatible, the FZP material cannot have electromagnetic interaction. In this work, a Phase-Reversal FZP (PR-FZP) made of Polylactic Acid (PLA) manufactured with a commercial 3D printer is proposed as a better, more efficient and MRI compatible alternative to conventional Soret FZPs. Phase-Reversal lenses, unlike traditional FZPs, take advantage of all the incident energy by adding phase compensation regions instead of pressure blocking regions. The manufactured PR-FZP achieves 21.9 dB of focal gain, which increases the gain compared to a Soret FZP of its same size by a factor of 4.0 dB. Both numerical and experimental results are presented, demonstrating the improved focusing capabilities of these types of lenses.

Design Considerations for 3D Printed, Soft, Multimaterial Resistive Sensors for Soft Robotics.

Sensor design for soft robots is a challenging problem because of the wide range of design parameters (e.g., geometry, material, actuation type, etc.) critical to their function. While conventional rigid sensors work effectively for soft robotics in specific situations, sensors that are directly integrated into the bodies of soft robots could help improve both their exteroceptive and interoceptive capabilities. To address this challenge, we designed sensors that can be co-fabricated with soft robot bodies using commercial 3D printers, without additional modification. We describe an approach to the design and fabrication of compliant, resistive soft sensors using a Connex3 Objet350 multimaterial printer and investigated an analytical comparison to sensors of similar geometries. The sensors consist of layers of commercial photopolymers with varying conductivities. We characterized the conductivity of TangoPlus, TangoBlackPlus, VeroClear, and Support705 materials under various conditions and demonstrate applications in which we can take advantage of these embedded sensors.

3D-printing of arsenic sulfide chalcogenide glasses

The use of a 3D-printing additive manufacturing process is reported for the first time for the extrusion of chalcogenide glasses by using a filament feed. Several challenges were overcome: preparation of chalcogenide glass filaments by the crucible technique, optimization of extrusion temperature or even filament feeding. The As40S60 chalcogenide glass was selected for its low glass transition temperature (Tg = 188°C) and ease of synthesis and processing. It was extruded using a commercial 3D-printer at a temperature around 140°C above the glass transition temperature. 3D-printed glass specimens were then characterized and no significant difference was observed in comparison with the bulk precursor glass in terms of chemical and thermal properties. This first report of additive manufacturing of chalcogenide glass complex shapes paves the way for the development of novel specialty optical components that could not be produced by conventional methods, including the fabrication of multimaterial optical fiber preforms.

3D-printed membrane microvalves and microdecoder

A microfluidic system for multichannel switching and multiphase flow control has potential uses in pneumatic soft robotics and biological sampling systems. At present, the membrane microvalves used in microfluidic systems are mostly constructed using a multilayer bonding process so that the device cannot withstand high pressures. In this paper, we demonstrate a design method and the properties of a bondless membrane microvalve fabricated using a commercial 3D printer. We used a multijet (MJP) 3D printer to print a 100-μm-thick and 6-mm-diameter membrane from a relatively hard material (1700 MPa). The membrane’s high toughness ensures that it does not need negative pressure to reopen. The measured operation frequency was less than 2.5 Hz under a pneumatic pressure of 14.5 kPa. We also 3D-printed an integrated Quake-style microfluidic decoder network by combining 8 valves in series to demonstrate the integrability of the microvalve. The decoder chip was demonstrated to control the ON/OFF state of the four coded fluidic channels, with the droplets being generated from selected channels according to the valve action. Therefore, such 3D-printed microvalves are highly integrable, have a high manufacturing efficiency, and can be applied in pneumatic controllers, sample switchers and integrated print heads.